N-Acetyl-L-cysteine is a compound widely used for treating chronic obstructive airway diseases/chronic bronchitis (for further references see Multicentre Study Group. Long-term oral acetylcysteine in chronic bronchitis. A double-blind controlled study. Eur. J. Respir. Dis. 1980, 61 (suppl. 111), 93-108; Bowman, G., Backer, U., Larsson, S., Melander, B., and W.ang.hlander, L. Oral acetylcysteine reduces exacerbation rate in chronic bronchitis. Report of a trial organized by the Swedish Society for Pulmonary Disease. Eur. J. Respir. Dis. 1983, 64, 405-415; and British Thoracic Society Research Committee. Oral N-acetylcysteine and exacerbation rates in patients with chronic bronchitis and severe airway obstruction. Thorax 1985, 40, 832-835). The mechanism of action of the compound is not disclosed; its effect has been attributed to mucolytic properties (see Multicentre Study Group. Long-term oral acetylcysteine in chronic bronchitis. A double-blind controlled study. Eur. J. Respir. Dis. 1980, 61 (suppl. 111), 93-108; Boman, G., Backer, U., Larsson, S., Melander, B., and W.ang.hlander, L. Oral acetylcysteine reduces exacerbation rate in chronic bronchitis. Report of a trial organized by the Swedish Society for Pulmonary Disease. Eur. J. Respir. Dis. 1983, 64, 405-415; and British Thoracic Society Research Committee. Oral N-acetylcysteine and exacerbation rates in patients with chronic bronchitis and severe airway obstruction. Thorax 1985, 40,832-835), antioxidant properties (see Aruoma, O.I., Halliwell, B., Hoey, B. M., and Butler, J. Free Radical Biol. Mad. 1989, 6, 593-597), and also immunomodulating properties (see Bergstrand, H., Bjornson, A., Eklund, A., Hernbrand, R., Eklund, A., Larsson, K., Linden M., and Nilsson, A. Stimuli-induced superoxide radical generation in vitro by human alveolar macrophages from smokers: Modulation by N-Acetylcysteine treatment in vivo. J. Free Radicals Biol. & Med. 2, 1986, 119-127).
The present invention deals with the disulfide of N-acetylcysteine, that is N,N'-diacetylcystine (in the following referred to as DiNAC), i.e. the compound of the formula: ##STR1##
N,N'-dibutyrylcystine (in the following referred to as diBUT), i.e. the compound of the formula: ##STR2##
N,N'-diisovalerylcystine (in the following referred to as diBUT), i.e. the compound of the formula: ##STR3##
N,N'-dicaprylylcystine (in the following referred to as diCAP), i.e. the compound of the formula ##STR4##
N,N'-diacetylcystine dimethyl ester ( in the following referred to as diMeNAC), i.e. the compound of the formula: ##STR5##
N,N'-diacetylcystine diethyl ester (in the following referred to as diEtNAC), i.e. the compound of the formula: ##STR6## and N,N'-diisovalerylcystine dimethyl ester (in the following referred to as diMeVAL), i.e. the compound of the formula: ##STR7##
The invention deals with the above mentioned compounds in racemic form as well as the isomeric D and L forms of the compounds. Of particular interest are the compounds having the L configuration, particularly interesting is N,N'-diacetyl-L-cystine.
The invention also deals with the compounds in the form of their physiologically acceptable salts such as the salts of sodium, potassium, ammonium, calcium or magnesium. Also included are salts of the compounds dINAC, diBUT, diVAL and diCAP with pharmaceutically acceptable organic bases.
The above mentioned compounds have previously been described in the patent literature as well as in the scientific literature. DiNAC in the following publications: U.S. Pat. No. 4,827,016; EP 300100; U.S. Pat. No. 4,724,239; U.S. Pat. No. 4,708,965; DE 2326444; Wilson, I. D., and Nicholson, J. K. Analysis of thiols and disulfides in Sulphur-containing drugs and related organic compounds. Chemistry, Biochemistry an Toxicology (ed L. A. Damani) Vol. 2A. Analytical, biochemical and toxicological aspects of sulphur xenobiochemistry. Ellis Horwood Series in Biochemical Pharmacology (Halstred Press: a division of John Wiley & Sons) Chichester 1989, p. 45; and Sjodin K., Nilsson E., Hallberg, A., and Tunek, A. Metabolism of N-Acetyl-L-cysteine. Some structural reguirements for the deacetylation and consequences for the oral biovailability. Biochem. Pharmacol. 1989, 38, 3981-3985). In U.S. Pat. No. 4,827,016 the compound is claimed to be effective for topical treatment of dermal inflammations which are induced and propagated by leukotrienes.
The remaining compounds have also been described in the literature. (See for instance, for diMeNAC: Bowman, W. R. Richardson, G. D. Tetrahedron Lett. 1981, 22, 1551-1554; for diEtNAC: Damico, R. A. Boggs, R. W. U.S. Pat. No. 3,952,115 (1976); for diVAL, diMeVAL: Martin, T. A. J. Med. Chem 1969, 12, 950-953), for diCAP: FR 8205 M, for diBUT: FR 2503151).
Nothing is reported or generally known concerning the pharmacological and/or therapeutic properties of these compounds with respect to immunological systems or inflammatory diseases of the lung such as chronic bronchitis.